This project aims at the understanding of the structure and mechanism of action of human erythrocyte carbonic anhydrases B and C in order to assess their physiological function and its inhibition and regulation by metabolites and drugs. Especial emphasis is currently placed on using chemical modification of the active sites of the enzymes in conjunction with carbon-13 nuclear magnetic resonance observations. The role of the essential zinc of the enzyme is being investigated through metal replacement studies. The interaction of the enzymes with sulfonamide inhibitors (drugs) is also being studied at the molecular level using physical and chemical techniques.